大功率天然气船用主机控制系统研究

从分析纯天然气船用主机启动、监测、调速、安全保护控制功能入手,并探讨了天然气燃料主机的系统配置框架结构和负载变化区域内的调速控制模式,设计出了一种符合船级社规范的新型大功率天然气主机控制系统,并突出了该控制系统的可靠性和负荷控制的稳定性、快速响应等特点。     

3D numerical modeling of wave forces on tandem fixed cylinders using the BEM

In this paper a 3D numerical model was developed to study the complicated interaction between waves and a set of tandem fixed cylinders.The fluid was considered to be inviscid and irrotational.Therefore,the Helmholtz equation was used as a governing equation.The boundary element method（BEM） was adopted to discretize the relevant equations.Open boundaries were used in far fields of the study domain.Linear waves were generated and propagated towards tandem fixed cylinders to estimate the forces applied on them.Special attention was paid to consideration of the effect on varying non-dimensional cylinder radius and distance between cylinders,ka and kd on forces and trapped modes.The middle cylinder wave forces and trapped modes in a set of nine tandem cylinders were validated utilizing analytical data.The comparisons confirm the accuracy of the model.The results of the inline wave force estimation on n tandem cylinders show that the critical cylinder in the row is the middle one for odd numbers of cylinders.Furthermore the results show that the critical trapped mode effect occurs for normalized cylinder radiuses close to 0.5 and 1.0.Finally the force estimation for n tandem cylinders confirms that force amplitude of the middle cylinder versus normalized separation distance fluctuates about that of a single cylinder.     

Capacity-constrained traffic forecasting model

Projecting future traffic is an important stage in any traffic and transportation planning study. Accurate traffic forecasting is vital for transportation planning, highway safety evaluation, traffic operations analysis, and geometric and pavement design among others. In view of its importance, this paper introduces a regression-based traffic forecasting methodology for a one dimensional capacity-constrained highway. Five different prediction functions are tested; the best was selected according to the accuracy of projections against historical traffic data. The three-parameter logistic function produced more accurate projections compared to other functions tested when highway capacity constraints were taken into consideration. The R ² values at various test locations ranged from 88% to 98%, indicating good prediction capability. Using the Fisher's information matrix approach, the t-statistic test showed all parameters in the logistic function were highly statistically significant. To evaluate reliability of projections, predictive intervals were calculated at a 95% level of confidence. Predictions using the logistic function were also compared to those predicted using the compound growth rate and linear regression methods. The results show that the proposed methodology generates much more reasonable projections than current practices.     

宁波市环城南路快速路(西延)工程总体设计

介绍了宁波市环城南路西延快速路的工程概况与建设背景,论证了工程的技术标准与建设规模,重点阐述了总体设计方案,主要包括功能定位、总体走向布置、横断面设计以及立交节点设计等。     

园区公共交通系统规划思路和要点

针对园区公共交通需求日益增强的情况,系统分析园区公交的存在问题和产生原因,结合相关工作经验,系统梳理园区公交系统的规划流程。从园区公交的功能定位、需求预测、规模分析、运营车辆、线路布设和收费模式等过程出发,明确规划思路和要点。并结合北京市丰台科技园东区园区公交规划项目,进行应用实例分析。     

沥青分子聚集状态变化特征研究

为研究沥青的化学结构特征,根据沥青组分溶解度参数和极性的不同,将沥青分为沥青质、胶质、油分3个组分,分别采用一个典型分子模型代表沥青的每一个组分,构建2种沥青分子模型,采用分子动力学模拟方法对沥青分子聚集状态变化特征进行分析.结果表明:由于π-π效应,沥青质分子之间形成层状堆积现象,但较长烷烃链造成芳环间扭转角增大,阻碍层状堆积现象的形成;随着温度升高,芳环间扭转角增大,沥青质分子之间的层状堆积结构被破坏,形成穿插或垂直排列结构;在沥青分子模型中,胶质和油分分子的存在使沥青质分子间的距离大于沥青质分子模型中的距离,也使沥青质分子间形成的聚集结构趋于稳定;沥青质与胶质分子形成聚集结构,分散在油分中,沥青质分子结构对沥青能否形成稳定胶体结构具有重要影响.     

公路项目质量保证成本估算模型构建与运用

为预估公路保证成本,进而规划、有效控制和适时拨付保证成本、指导各部门实践,在剖析国内外研究趋势基础上,引入公路项目失效函数理论,分析了失效因子与质量保证的关系;随后基于个体失效模式、可靠性、随机过程,构建了公路项目失效函数;并以某公路项目为例对长期质量保证下横向裂缝与车辙2个指标进行质量保证期期望维修成本和保证风险成本进行估算;以此为基础对政策制订、发包商的招标行为、承包商的投标与施工行为、质量保证资源协调控制进行了分析,最后对估算模型现实运用的扩展性进行了说明.     

智能交通在城市交通中的应用探讨

智能交通的研究课题是如何把现代的高科技与交通联系起来.结合实际阐述了智能交通系统在城市交通管理中的作用和重要性,针对我国交通现状提出了一些建议,并对智能交通未来的发展进行了探讨.     

图的符号边控制与减边控制

设G是一个图,γ′s(G)和γ′m(G)分别表示图G的符号边控制数和减边控制数,利用图的边度序列给出了γ′s(G)和γ′m(G)的下限,并通过图G的子图明确了两者的关系,为找出γ′m(G)更多的下界提供了新的方法。     

功能叠加型立交改造方案设计探讨

随着社会经济的发展,交通量迅速增长,路网不断更新升级,早年的高速公路面临改扩建的问题,而建成区多种功能叠加的高速公路立交布设成为改扩建的重点和难点。以广深高速鹤州立交改造工程为例,探讨重交通量下高速公路功能叠加型立交改扩建设计的技术思路,分析设计中遇到的问题,总结相应的设计原则并提出具体的方案。